Deposition Corrosion of Galvanized Steel in the Presence of Copper

Abstract

Deposition corrosion, via formation of microgalvanic cells from copper ions (e.g., Cu + , Cu 2+ ) on iron or galvanized (zinc coated) steel pipes, has been linked to disastrous field corrosion failures.Key factors expected to control deposition corrosion, including soluble copper concentration, copper ion speciation, and flow pattern (stagnant versus recirculating), were examined. The mass of copper plated was directly proportional to the soluble copper concentration in solution.The presence of flow, which allowed greater mass transport of reactants to the pipe surface, proved to be crucial to replicating deposition corrosion in the laboratory: tests with flow demonstrated up to 7X more zinc release and 55X more iron release when copper was present than when it was absent, compared to increases of only ≈2X in the same water under stagnant conditions. Scale dissolution, x-ray fluorescence (XRF), and scanning electron microscopy (SEM) were used to characterize copper-rich deposits on the surface of both field and laboratory samples that were consistent with metallic copper, supporting a deposition corrosion mechanism.

Impact of Road Salt on Drinking Water Quality and Infrastructure Corrosion in Private Wells

“…The selected 12 solder joints had an average copper level of 853 ± 49 μg/L and average lead of 59.1 ± 9.5 μg/L. To examine deposition corrosion (plating of dissolved copper on metal surfaces and resulting corrosion of the microgalvanic cells), 32 iron and zinc wires were also exposed to the four chloride water conditions with 3 mg/L cuprous chloride (CuCl) as copper (Cu) added. For these conditions, the amounts of NaCl added to the synthetic waters were adjusted to maintain the target chloride concentrations.…”

“…We speculate that the iron wire with copper was oxidized to form iron(III) protective layers, which prevented further corrosion. 32 Overall, aged galvanized iron pipes would be expected to experience increased corrosion for very high chloride waters, but not weight loss in the presence of road salt.…”

Utility considerations in developing a galvanized iron water pipe management plan

“…In a more recent national survey, approximately 35% (21 out of 60) of drinking water systems expressed concerns about GIP corrosion (Arnold et al, 2020). In the 1970s, GIP experienced high‐profile leak failures, partly due to inadequate zinc coatings inside the pipe and partly due to deposition corrosion from installation of upstream copper (Clark & Edwards, 2016; Fox et al, 1986). It was around this time that some cities started banning GIP via plumbing code revisions because of its unpredictable and unsatisfactory performance compared with copper, polyvinyl chloride (PVC), and other modern plumbing materials (Sheehan, 2016; Tang, Nystrom, et al, 2018).…”

“…GIP can be a major cause of tap water discoloration due to mobilization of Fe particles from pipe scale (Clark et al, 2015; Clark & Edwards, 2016; Masters & Edwards, 2015; McGuire & Pearthree, 2018; Pieper et al, 2017; Tang, Nystrom, et al, 2018) (Figure 2). However, there are other sources of water discoloration including Fe and manganese from source water passing through the treatment facility (Schock & Giani, 2004; Tobiason et al, 2016), mobilization of legacy deposits in the distribution system (Brandhuber, 2013), and corrosion of unlined cast Fe distribution mains (McNeill & Edwards, 2001) which need to be considered when evaluating causes of discolored water.…”

Impact of iron‐rich scale in service lines on lead release to water

“…Such retardation can occur in response to the conditions of pH, DIC, or disinfectants (Liu, Korshin, & Ferguson, 2008; Lytle & Schock, 2005; Schock, 1980; Zhang & Lin, 2011). The connection of lead to metals such as copper, brass, or steel can also induce galvanic corrosion, with accompanying release of lead (Clark et al, 2013; Clark & Edwards, 2016; Clark, St. Clair, & Edwards, 2015; Kimbrough, 2007; Wang, Jing, Mehta, Welter, & Giammar, 2012; Wang, Mehta, Welter, & Giammar, 2013).…”